Success Criterion 3.1.2 (Language of Parts) states that the changes in language should be marked using language attributes to qualify for AA conformance.
This example should successfully test the usage of lang and xml:lang attributes on a normal element.
Note: This example document is a HTML serialisation of HTML5, which explicitly allows both "lang" and "xml:lang" - but only the former takes effect, as in HTML 4.01. (If this were XHTML, the latter would prevail, as per the XML definition.) In HTML 4.01 and earlier, the presence of "xml:lang" would make the document invalid, although not necessarily failing any Success Criteria.
(The "*" represents either "Lang" or "XmlLang" depending on which attribute applies.)